Speech Coding Algorithms: Foundation and Evolution of Standardized Coders

Speech coding is a highly mature branch of signal processing deployed in products such as cellular phones, communication devices, and more recently, voice over internet protocol This book collects many of the techniques used in speech coding and presents them in an accessible fashion Emphasizes the foundation and evolution of standardized speech coders, covering standards from 1984 to the present The theory behind the applications is thoroughly analyzed and proved

Table of Contents:
Preface xiii Acronyms xix Notation xxiii 1 Introduction 1 1.1 Overview of Speech Coding 2 1.2 Classification of Speech Coders 8 1.3 Speech Production and Modeling 11 1.4 Some Properties of the Human Auditory System 18 1.5 Speech Coding Standards 22 1.6 About Algorithms 26 1.7 Summary and References 31 2 Signal Processing Techniques 33 2.1 Pitch Period Estimation 33 2.2 All-Pole and All-Zero Filters 45 2.3 Convolution 52 2.4 Summary and References 57 Exercises 57 3 Stochastic Processes and Models 61 3.1 Power Spectral Density 62 3.2 Periodogram 67 3.3 Autoregressive Model 69 3.4 Autocorrelation Estimation 73 3.5 Other Signal Models 85 3.6 Summary and References 86 Exercises 87 4 Linear Prediction 91 4.1 The Problem of Linear Prediction 92 4.2 Linear Prediction Analysis of Nonstationary Signals 96 4.3 Examples of Linear Prediction Analysis of Speech 101 4.4 The Levinson–Durbin Algorithm 107 4.5 The Leroux–Gueguen Algorithm 114 4.6 Long-Term Linear Prediction 120 4.7 Synthesis Filters 127 4.8 Practical Implementation 131 4.9 Moving Average Prediction 137 4.10 Summary and References 138 Exercises 139 5 Scalar Quantization 143 5.1 Introduction 143 5.2 Uniform Quantizer 147 5.3 Optimal Quantizer 149 5.4 Quantizer Design Algorithms 151 5.5 Algorithmic Implementation 155 5.6 Summary and References 158 Exercises 158 6 Pulse Code Modulation and Its Variants 161 6.1 Uniform Quantization 161 6.2 Nonuniform Quantization 166 6.3 Differential Pulse Code Modulation 172 6.4 Adaptive Schemes 175 6.5 Summary and References 180 Exercises 181 7 Vector Quantization 184 7.1 Introduction 185 7.2 Optimal Quantizer 188 7.3 Quantizer Design Algorithms 189 7.4 Multistage VQ 194 7.5 Predictive VQ 216 7.6 Other Structured Schemes 219 7.7 Summary and References 221 Exercises 222 8 Scalar Quantization of Linear Prediction Coefficient 227 8.1 Spectral Distortion 227 8.2 Quantization Based on Reflection Coefficient and Log Area Ratio 232 8.3 Line Spectral Frequency 239 8.4 Quantization Based on Line Spectral Frequency 252 8.5 Interpolation of LPC 256 8.6 Summary and References 258 Exercises 260 9 Linear Prediction Coding 263 9.1 Speech Production Model 264 9.2 Structure of the Algorithm 268 9.3 Voicing Detector 271 9.4 The FS1015 LPC Coder 275 9.5 Limitations of the LPC Model 277 9.6 Summary and References 280 Exercises 281 10 Regular-pulse Excitation Coders 285 10.1 Multipulse Excitation Model 286 10.2 Regular-Pulse-Excited–Long-Term Prediction 289 10.3 Summary and References 295 Exercises 296 11 Code-excited Linear Prediction 299 11.1 The CELP Speech Production Model 300 11.2 The Principle of Analysis-by-Synthesis 301 11.3 Encoding and Decoding 302 11.4 Excitation Codebook Search 308 11.5 Postfilter 317 11.6 Summary and References 325 Exercises 326 12 The Federal Standard Version of CELP 330 12.1 Improving the Long-Term Predictor 331 12.2 The Concept of the Adaptive Codebook 333 12.3 Incorporation of the Adaptive Codebook to the CELP Framework 336 12.4 Stochastic Codebook Structure 338 12.5 Adaptive Codebook Search 341 12.6 Stochastic Codebook Search 344 12.7 Encoder and Decoder 346 12.8 Summary and References 349 Exercises 350 13 Vector Sum Excited Linear Prediction 353 13.1 The Core Encoding Structure 354 13.2 Search Strategies for Excitation Codebooks 356 13.3 Excitation Codebook Searches 357 13.4 Gain Related Procedures 362 13.5 Encoder and Decoder 366 13.6 Summary and References 368 Exercises 369 14 Low-delay CELP 372 14.1 Strategies to Achieve Low Delay 373 14.2 Basic Operational Principles 375 14.3 Linear Prediction Analysis 377 14.4 Excitation Codebook Search 380 14.5 Backward Gain Adaptation 385 14.6 Encoder and Decoder 389 14.7 Codebook Training 391 14.8 Summary and References 393 Exercises 394 15 Vector Quantization of Linear Prediction Coefficient 396 15.1 Correlation Among the LSFs 396 15.2 Split VQ 399 15.3 Multistage VQ 403 15.4 Predictive VQ 407 15.5 Summary and References 418 Exercises 419 16 Algebraic CELP 423 16.1 Algebraic Codebook Structure 424 16.2 Adaptive Codebook 425 16.3 Encoding and Decoding 433 16.4 Algebraic Codebook Search 437 16.5 Gain Quantization Using Conjugate VQ 443 16.6 Other ACELP Standards 446 16.7 Summary and References 451 Exercises 451 17 Mixed Excitation Linear Prediction 454 17.1 The MELP Speech Production Model 455 17.2 Fourier Magnitudes 456 17.3 Shaping Filters 464 17.4 Pitch Period and Voicing Strength Estimation 466 17.5 Encoder Operations 474 17.6 Decoder Operations 477 17.7 Summary and References 481 Exercises 482 18 Source-controlled Variable Bit-rate CELP 486 18.1 Adaptive Rate Decision 487 18.2 LP Analysis and LSF-Related Operations 494 18.3 Decoding and Encoding 496 18.4 Summary and References 498 Exercises 499 19 Speech Quality Assessment 501 19.1 The Scope of Quality and Measuring Conditions 501 19.2 Objective Quality Measurements for Waveform Coders 502 19.3 Subjective Quality Measures 504 19.4 Improvements on Objective Quality Measures 505 Appendix A Minimum-phase Property of the Forward Prediction-error Filter 507 Appendix B Some Properties of Line Spectral Frequency 514 Appendix C Research Directions in Speech Coding 518 Appendix D Linear Combiner for Pattern Classification 522 Appendix E CELP: Optimal Long-term Predictor to Minimize the Weighted Difference 531 Appendix F Review of Linear Algebra: Orthogonality, Basis, Linear Independence, and the Gram–schmidt Algorithm 537 Bibliography 542 Index 553

About the Author :
WAI C. CHU earned a PhD in Electrical Engineering from the Pennsylvania State University. His industry experience includes positions at Texas Instruments and various startup companies in the multimedia field. Currently at DoCoMo USA Labs (San Jose, California), he is involved with R&D activities in speech/audio coding, digital signal processing, and multimedia applications.

Review :
“…well equipped with exercises and with procedures which are helpful in implementing the coders…” (Zentralblatt Math, Vol.1041, No.16, 2004)